How could it explain that diabetics lived longer than healthy people?
If all of the sickest diabetics are switched to other drugs, then the only people taking metformin are the ‘healthy diabetics’, and it is possible that the average healthy diabetic lives longer than the average person (who may be healthy or unhealthy).
This would give the observed effective without metformin having any effect on longevity.
How could it explain that diabetics lived longer than healthy people?
Anyway, we need a direct test on healthy people to know if it works or not.
If all of the sickest diabetics are switched to other drugs, then the only people taking metformin are the ‘healthy diabetics’, and it is possible that the average healthy diabetic lives longer than the average person (who may be healthy or unhealthy).
This would give the observed effective without metformin having any effect on longevity.